Original DescriptionThe low trochospirally coiled test is covered with an incipient development of costellae. All chambers are inflated and globigerine-like, but later ones show a slight degree of compression. The last whorl is scalloped and composed of 5-6 chambers. Some or all later chambers exhibit a very weak double-keeled, imperforate, peripheral band. The 2 keels are very faint and may be missing from a few of the last chambers. The costellae which are barely discernible, give the surface a roughened appearance. The principal aperture is rounded, interiomarginal, and open into a rather large umbilicus. Long apertural flaps extend into the umbilicus, and in later chambers form a protruded, imperforate, umbilical cover-plate with accessory apertures.Etymology: This species is named for Brooks F. Ellis in recognition of his contributions to micropaleontology.Extra details from original publicationRemarks:Rugotruncana ellisi, n. sp., is the most primitive species of Rugotruncana. It resembles the genotype, Rugotruncana tilevi, n. sp., but its chambers are not as compressed, and it keels and costellae are weaker. It is similar to Globotruncana saratogaensis (Applin), but the latter has no costellae.

Rugotruncana ellisi, n. sp., has been observed by us in the upper Taylor marl (Campanian). It is abundant in the Corsicana marl (lower Maastrichtian) and Kemp clay (middle Maastrichtian) of the Navarro group in Texas, and in the Arkadelphia formation of the Navarro group in Arkansas.